One method employed in the past in the field of cataract surgery involves extracting the intracapsular crystalline lens through a surgical incision made in ocular tissue such as the cornea (sclera) or anterior capsule section of the crystalline lens, and once the crystalline lens has been removed, inserting an intraocular lens serving as a replacement for the crystalline lens back through the incision and positioning it within the capsule.
Particularly in recent years, methods that employ an intraocular lens insertion tool like that disclosed in Patent Document 1 and Patent Document 2 have come into widespread use. Typically, the intraocular lens will be inserted into the eye by first inserting the distal orifice of an insertion tube provided at the distal end section of the body of the tool through a surgical incision, then pushing the intraocular lens (which has been maintained in a state of compact deformation inside the body of the tool) out through the distal orifice of the insertion tube.
By employing such an insertion tool, the intraocular lens can be inserted into the eye without expanding the surgical incision that was made for the purpose of extracting the crystalline lens, thereby reducing the labor entailed in the surgical operation, as well as reducing the risk of post-surgical astigmatism or infection.
Problems encountered with such conventional insertion tools include a tendency for the intraocular lens to rotate inside the insertion tube or to flip front to back as the intraocular lens is pushed along.
In order to deal with such problems, there has been proposed in Patent Document 3, for example, an insertion tool in which the shape of the inside face of the insertion tube is a discontinuous shape having an inflection point, designed so that the intraocular lens becomes lodged at the inflection point so as to prevent it from rotating.
However, an insertion tool constructed in this manner poses a risk that due to becoming lodged in this way, the intraocular lens may experience unnecessary bending or be subjected to localized action of excessive levels of deformation or stress. For this reason, the insertion resistance of the intraocular lens will be greater, with an attendant risk or deformation or damage when forcibly pushed. An additional difficulty is the problem, in terms of the mold etc., of forming an inflection point having a sufficiently acute angle to hold up the intraocular lens and prevent it from rotating.
Patent Document 1: JP-A-2002-525023
Patent Document 2: JP-A-11-506357
Patent Document 3: Japanese Patent No. 3420724